Antennas for receiving and transmitting radio frequency or other high frequency electromagnetic signals are typically sensitive to the orientation between the transmitting and receiving antennas. In addition, it is generally advantageous to provide a direct line of sight between the transmitting and receiving antennas with no obstacles interfering with that line of sight. In particular, it is disadvantageous to interpose a metallic member between the transmitting and receiving antennas.
One example of a system in which line of sight and orientation are critical is the use of antenna assemblies in conjunction with the geostationary constellations of artificial satellites for positioning purposes. For example, an antenna assembly mounted on a vehicle must maintain line of sight communication with members of the satellite constellation to provide the best datalink between the satellite members and the vehicle antenna. In addition, the antenna assemblies typically used with vehicles are polarized for operation in a specific orientation with respect to the satellite constellation. Therefore, angular rotation of the antenna assembly relative to the satellite constellation is likewise disadvantageous.
It is known in the art to provide various mechanisms for maintaining antenna assemblies in a specific orientation. Some of the prior art systems include counterweight stabilized antenna assemblies mounted in a gimbaled or multirotational fashion. However, none of the prior art antenna assemblies were specifically designed to deal with the combination of line of sight and rotational orientation problems encountered in the case of an antenna used with a vehicle having a dump bed. Antennas mounted on such vehicles, including large off-road mining vehicles, are typically attached to a cab or other stationary portion of the vehicle. However, elevation of the dump bed on such vehicles interposes a metallic element between the stationary mounted antenna and the satellite constellation. This interferes with the line of sight communication requires for best operation of the antenna assembly. Further, the antenna needs to be stabilized when the dump bed is in the lowered or normal carrying mode to prevent undulations in the ground and ordinary travel vibration from causing the gimbaled antenna to oscillate or vibrate in its mounting.
Attempts have also been made to mount the antenna to the dump bed itself, in such a manner that the antenna is elevated along with the leading edge of the dump bed. Such mounting overcomes the line of sight communication problem but then misorients the antenna as the angular relationship between the edge of the dump bed and the constellation system changes.
The present invention is intended to address and overcome one or more of the problems set forth above. The instant antenna assembly and assembly mount are adapted for connection to the edge of a vehicle dump bed, are gimbaled to maintain a constant. orientation relative to the satellite constellation, and include a damping mechanism specifically designed to overcome the vibration and oscillation caused by driving such a vehicle over rough terrain.